PIVOVARCHIK, V. N.; BOYKO, O. P. Inverse spectral problem for a star graph of Stieltjes strings. Methods of Functional Analysis and Topology, [S. l.], v. 14, n. 2, p. 159–167, 2008. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/379. Acesso em: 18 dec. 2025.